1. Technical Field
The present disclosure relates to a receiver for a signal communication apparatus and related signal communication apparatus and methods.
2. Description of the Related Art
Galvanic isolation is used in applications in which the communication between circuits operating at high supply voltages (even hundreds of volts) and circuits rather operating at low supply voltages; the galvanic isolation provides for the safety of the user coming in contact with the low voltage interface. The applications using galvanic isolation are typically those regarding the power supplies directly bonded to the power network, and also the industrial applications in which driving high voltage loads occurs.
A typical example are the “high side switch drivers” in which driving switches feed inductive loads with high voltages. In such a case the potential differences that may dynamically develop between the low voltage part and the high voltage part may also reach thousands of volts per microsecond.
Several apparatuses for achieving the galvanic isolation presently exist.
One of these uses an integrated transformer. The latter is made of a pile structure in which the secondary winding generally has a metal layer arranged at the lowermost level, the primary winding has a metal layer arranged at the uppermost level and the isolation between the two windings comprises several layers of dielectric arranged between the two metal layers the thickness of which depends on the desired isolation level. Alternatively, the secondary winding may be made of the metal layer arranged at the uppermost level, the dielectric layer is inserted thereon and the primary winding is finally made of an additional metal layer. The isolation transformer is made on the die of the receiver. The die driver contains the transmitter that, through the bonding, is bonded to the primary of the isolation transformer. The secondary of the transformer is bonded to the receiver which processes the transmitted signal. The data flow may also occur from the secondary to the primary, in case of constructing a two-way channel. In order to transfer information through the isolated interface, the signals are conveniently processed by a modulation technique. This type of component permits to obtain a high bit rate, good reliability and isolation capacity. This configuration uses, however, the addition of processing steps to construct the transformer (e.g., for increasing the thickness of the isolating layer in order to achieve the suitable isolation rate), as well as the use of bonding wires for bonding the transmitter of the die driver to the transformer itself.
Another galvanic isolation apparatus comprises a structure based on a transmission of the wireless type and it is described in US Patent Publication No. US 2008/0311862. The two chips are assembled one on top of the other and the isolation is achieved through an interposed isolating layer. The electromagnetic coupling is obtained through a couple of turns, particularly by means of the magnetic field produced by the power flowing on the transmitting turn. The thickness of the upper chip (e.g., the chip of the transmitter) is decreased, by lapping, to maximize the coupling between the two turns. In order to transfer information through the isolated interface, the signals are conveniently processed by a modulation technique. This configuration has the advantage of not requiring additional processing steps as well as bonding wires between the two chips. It has however the disadvantage of a low coupling coefficient and its high variability, depending on the thickness tolerance after the die lapping, the tolerance of the isolating layer thickness and the tolerance of the alignment between the two chips.
A further galvanic isolation apparatus comprises a structure based on a transmission of the wireless type and it is still described in US Patent Publication No, 2008/0311862. The two chips, in this case, are assembled side-by-side and the isolation is made through an isolating layer placed under the two chips. The electromagnetic coupling is achieved through a couple of turns, particularly by means of the magnetic field produced by the power flowing on the transmitting turn. In order to transfer information through the isolated interface, the signals are conveniently processed by a modulation technique. This configuration also has the advantage of not requiring additional processing steps as well as bonding wires between the two chips. It has however the disadvantage of a coupling coefficient which is lower than the previous structure and highly variable according to the tolerance of the alignment between the two chips and the tolerance of the distance between the two chips.